In many contexts, there is a manifest interest in establishing muscular status, by which is taken to mean both the status of muscle at rest and the status of muscle at work. It is of particular interest to be able to follow the change in the status of the muscle during work and, in such instance, preferably to obtain a continuous and/or immediate information on status with the possibility of recording this for subsequent follow-up.
Such establishment of muscular status is, of course, interesting in purely scientific contexts and in the event of illnesses, but is also of considerable value in many practical applications, for example of people carrying out industrial assembly work or certain types of office work (e.g. terminal work at computers). By establishing muscular status, the possibility will be created, for example, for studying the effect of the design and layout of the workplace and the working position, respectively, on muscle loading, and for analyzing the consequences of prolonged monotonous muscle loading. This latter working situation occurs in both the assembly industry and in office work.
A correct establishment of muscular status in lengthy loading would make it possible, at best, to wholly avoid the risk of chronic muscular disorder or could be used to identify those stages of labor, which, for a given individual, cause, for instance chronic pain. The information would make it possible to modify the design of tools or the workplace in order to avoid such problems or resulting injuries. In particular, real time knowledge of the state of the muscles e.g. the state of fatigue of the muscles or muscle inactivity could be essential in evaluating the effect of the work involved on the muscles.
It is obvious that there is also a need in this art for a technique for continuous recording of muscular status. Such a technique would, thus, make it possible to establish how muscular fatigue changes during a work shift or a series of work shifts, at the same time as such recording would make it possible to objectively analyze and identify how changes in the design of the workplace, for example the design of auxiliary aids, tools etc. influence the degree of muscular fatigue and its development in prolonged work. It should be observed that, at low muscular loading which is continuous for a lengthy time, the individual himself does not observe that the muscle becomes fatigued. There are firm grounds for assuming that, when such situations exist, there is a risk of chronic muscular injury.
Also desirable is a technique which permits direct feedback to the individual of information concerning current muscular condition in order thereby to gain the possibility of warning, while work is in progress, of muscle loadings and stresses which risk resulting in injury.